Software for Telecoms & Audio
V.8 Modem DSP C Code
implements the ITU modem Recommendation V.8 for the standard 2-wire telephone
network. V.8 is used by data modems / fax machines developed since the
early 1990s to exchange operational menus. The V.8 signals are the initial
sequence exchanged following connect-to-line. They start with a modified
version of the 2100Hz auto-answer signal for disabling echo-control devices.
The operational menus are then exchanged using V.21 300b/s FSK modulation.
The Calling channel uses 980Hz(Mark) and 1180Hz(Space) tones whilst the
Answering channel uses 1650Hz(Mark) and 1850Hz(Space) keying tones. As
part of the menu exchange in V.8, the highest common denominator modulation
mode is chosen.
At the control interface, the code has one 16-bit control word to sequence operation and to set operating parameters, and one diagnostic word to convey the V.8 handshake status and to provide a modulation mode listing of the V.8 negotiation result.
- #example figures from compiling for the TI TMS320C5000(C55x) DSP processor
Availability: NOW - sale is under licence - integration support offered